Inertial force sensor

ABSTRACT

An inertial force sensor includes a detecting device which detects an inertial force, the detecting device having a first orthogonal arm and a supporting portion, the first orthogonal arm having a first arm and a second arm fixed in a substantially orthogonal direction, and the supporting portion supporting the first arm. The second arm has a folding portion. In this configuration, there is provided a small inertial force sensor which realizes detection of a plurality of different inertial forces and detection of inertial forces of a plurality of detection axes.

This application is a division of U.S. patent application Ser. No. 12/160,237 filed Jul. 8, 2008 which is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The present invention relates to an inertial force sensor which detects an inertial force used for various electronic devices, such as a posture controller or a navigation device, of a moving body, such as an airplane, an automobile, a robot, a ship, or a vehicle.

BACKGROUND ART

A conventional inertial force sensor will be described below.

An inertial force sensor which detects an inertial force, such as an angular velocity or acceleration, has been used. In the use of the conventional inertial force sensor, an exclusive angular velocity sensor is used to detect an angular velocity and an exclusive acceleration sensor is used to detect acceleration. When angular velocities and accelerations corresponding to a plurality of detection axes of an X-axis, a Y-axis, and a Z-axis orthogonal to each other are detected, a plurality of angular velocity sensors and a plurality of acceleration sensors according to the number of the detecting axes are used.

When various types of electronic devices combine and detect an angular velocity and acceleration or detect angular velocities and accelerations relative to a plurality of detection axes, a plurality of angular velocity sensors and a plurality of acceleration sensors are mounted on a mounting substrate of the electronic devices.

The angular velocity sensor oscillates a detecting device in tuning fork shape, H shape, or T shape and then electrically detects distortion of the detecting device with occurrence of a Force de Coriolis to detect an angular velocity. The acceleration sensor has a weight portion and compares and detects movement of the weight portion with acceleration with that before operation to detect acceleration.

Such conventional inertial force sensors, such as the angular velocity sensor and the acceleration sensor, are used for a posture controller or a navigation device of a moving body, such as a vehicle, according to an inertial force or a detection axis to be detected.

The conventional inertial force sensor is disclosed in Unexamined Japanese Patent Publication No. 2001-208546 (Patent Document 1) or Unexamined Japanese Patent Publication No. 2001-74767 (Patent Document 2).

-   [Patent Document 1] Unexamined Japanese Patent Publication No.     2001-208546 -   [Patent Document 2] Unexamined Japanese Patent Publication No.     2001-74767

DISCLOSURE OF THE INVENTION

The present invention provides a small inertial force sensor which does not require a large mounting area for mounting a plurality of inertial force sensors and can detect a plurality of different inertial forces, such as an angular velocity and acceleration, or inertial forces of a plurality of detection axes.

An inertial force sensor of the present invention includes a detecting device which detects an inertial force, the detecting device having a first orthogonal arm and a supporting portion, the first orthogonal arm having a first arm and a second arm fixed in a substantially orthogonal direction, and the supporting portion supporting the first arm. The second arm has a folding portion. With this configuration, there is provided a small inertial force sensor which realizes detection of a plurality of different inertial forces and detection of inertial forces of a plurality of detection axes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a plan view illustrating a detecting device used for an inertial force sensor according to exemplary embodiment 1 of the present invention.

FIG. 1B is an operation state diagram illustrating an operation state of the detecting device illustrated in FIG. 1A.

FIG. 2A is a plan view illustrating a detecting device according to another embodiment of exemplary embodiment 1 of the present invention.

FIG. 2B is a plan view illustrating a detecting device according to a further embodiment of exemplary embodiment 1 of the present invention.

FIG. 3 is an operation state diagram illustrating an operation state of an inertial force sensor according to exemplary embodiment 2 of the present invention.

FIG. 4A is a plan view illustrating a detecting device used for an inertial force sensor according to exemplary embodiment 3 of the present invention.

FIG. 4B is an operation state diagram illustrating an operation state of the detecting device illustrated in FIG. 4A.

FIG. 5A is a plan view illustrating a detecting device according to another embodiment of exemplary embodiment 3 of the present invention.

FIG. 5B is a plan view illustrating a detecting device according to a further embodiment of exemplary embodiment 3 of the present invention.

FIG. 6A is a plan view illustrating a detecting device used for an inertial force sensor according to exemplary embodiment 4 of the present invention.

FIG. 6B is an operation state diagram illustrating an operation state of the detecting device illustrated in FIG. 6A.

FIG. 7A is a plan view illustrating a detecting device according to another embodiment of exemplary embodiment 4 of the present invention.

FIG. 7B is a plan view illustrating a detecting device according to a further embodiment of exemplary embodiment 4 of the present invention.

FIG. 8A is a plan view illustrating a detecting device used for an inertial force sensor according to exemplary embodiment 5 of the present invention.

FIG. 8B is an operation state diagram illustrating an operation state of the detecting device illustrated in FIG. 8A.

FIG. 9 is a plan view illustrating a detecting device according to another embodiment of exemplary embodiment 5 of the present invention.

FIG. 10 is a perspective view of a detecting device according to a further embodiment of exemplary embodiment 5 of the present invention.

FIG. 11 is a plan view of a detecting device used for an inertial force sensor according to exemplary embodiment 6 of the present invention.

FIG. 12 is an operation state diagram illustrating an operation state of the detecting device illustrated in FIG. 11.

FIG. 13 is a plan view of a detecting device according to another embodiment of exemplary embodiment 6 of the present invention.

FIG. 14A is a plan view of a detecting device according to a further embodiment of exemplary embodiment 6 of the present invention.

FIG. 14B is a plan view of a detecting device according to a still another embodiment of exemplary embodiment 6 of the present invention.

REFERENCE MARKS IN THE DRAWINGS

-   1 Detecting device -   2 First arm -   4 Second arm -   4 a Folding portion -   4 b End -   6 First orthogonal arm -   7 Second orthogonal arm -   8 Supporting portion -   9 Base portion -   10 Fixing arm -   10 b End -   12 Third arm -   14 Fourth arm -   18 Weight portion -   20 Inertial force sensor

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Exemplary Embodiment 1

FIG. 1A is a plan view of a detecting device used for an inertial force sensor according to exemplary embodiment 1 of the present invention. FIG. 1B is an operation state diagram of the detecting device illustrated in FIG. 1A.

In FIG. 1A, inertial force sensor 20 has detecting device 1 which detects an inertial force and a processing circuit (not illustrated). Detecting device 1 has two first orthogonal arms 6 and supporting portion 8. Each of first orthogonal arms 6 has first arm 2 and second arm 4. First arm 2 is formed so as to be fixed to second arm 4 in a substantially orthogonal direction. Supporting portion 8 supports two first arms 2. Supporting portion 8 serves as base portion 9. When detecting device 1 is mounted on a mounting substrate (not illustrated), detecting device 1 is fixed to the mounting substrate using base portion 9. Second arm 4 is folded at folding portions 4 a so that ends 4 b of second arm 4 are arranged to be confronted with first arm 2. Weight portion 18 is formed at end 4 b of second arm 4.

In detecting device 1, first arm 2 and supporting portion 8 are arranged on a substantially identical straight line. Relative to an X-axis, a Y-axis, and a Z-axis orthogonal to each other, a longitudinal direction of first arm 2 is arranged in the Y-axis direction and a longitudinal direction of second arm 4 is arranged in the X-axis direction.

Detecting device 1 is integrally molded to a silicon substrate as a material. A driving electrode is arranged on an arm, which is driven and oscillated, on the silicon substrate. A detecting electrode is arranged on an arm, whose distortion is detected, on the silicon substrate. In detecting device 1 illustrated in FIG. 1A, end 4 b of second arm 4 is the arm which is driven and oscillated, and first arm 2 and second arm 4 are the arm whose distortion is detected. The driving electrode (not illustrated) is arranged on end 4 b. The detecting electrodes (not illustrated) are arranged on both of first arm 2 and second arm 4.

The driving electrode and the detecting electrode are formed by laminating a lower electrode, a piezoelectric element, and an upper electrode on the silicon substrate. The lower electrode is formed by high-frequency sputtering of Pt, for example. A PZT piezoelectric element is formed on the lower electrode by high-frequency sputtering, for example. The upper electrode is formed on the piezoelectric element by Au deposition, for example.

When an alternating voltage having a resonance frequency which resonates the silicon configuring detecting device 1 is applied between the lower electrode and the upper electrode, the arm on which the driving electrode is arranged is driven and oscillated. The arm is distorted due to an angular velocity and acceleration. A voltage according to the distortion is outputted from the detecting electrode arranged on the distorted arm. The processing circuit detects the angular velocity and the acceleration based on an output voltage outputted from the detecting electrode.

With the above configuration, as for an angular velocity, as illustrated in FIG. 1B, end 4 b of second arm 4 is driven and oscillated in the X-axis direction, for example. A distortion due to an angular velocity about the Z-axis is caused in the Y-axis direction of second arm 4. That is to say, a Force de Coriolis corresponding to the driving and oscillation is caused in the Y-axis direction of second arm 4. At the same time, a distortion due to an angular velocity about the Y-axis is caused in the Z-axis direction of second arm 4. Similarly, a Force de Coriolis corresponding to the driving and oscillation is caused in the Z-axis direction of second arm 4. The distortion caused in at least one of the Y-axis direction and the Z-axis direction of second arm 4 is detected to detect an angular velocity produced in detecting device 1. The driving and oscillation in the X-axis direction of end 4 b are driving and oscillation in which a solid arrow line and a dotted arrow line illustrated in FIG. 1B are repeated alternately, for example.

As for acceleration, as illustrated in FIG. 1B, a distortion due to acceleration in the X-axis direction is caused in first arm 2, similarly. That is to say, a force due to a deadweight of second arm 4 is added to first arm 2. At the same time, a distortion due to acceleration in the Y-axis direction is caused in second arm 4. That is to say, a force due to the deadweight of second arm 4 is added to second arm 4. The distortion caused in at least one of first arm 2 and second arm 4 is detected to detect acceleration produced in detecting device 1.

Thus, a plurality of different inertial forces added to detecting device 1 is detected. Inertial forces of a plurality of different detection axes added to detecting device 1 are detected. Detecting device 1 which reduces a mounting area and is miniaturized is realized.

In detecting device 1 of the present invention, end 4 b of second arm 4 is driven and oscillated, and second arm 4 has a shape folded at folding portion 4 a. Thus, detecting device 1 which has a small mounting area and is miniaturized is realized. In addition, a distance between driven and oscillated end 4 b of second arm 4 and base portion 9 to which detecting device 1 is fixed becomes substantially longer. Detection sensitivity of the angular velocity and the acceleration in each of the directions is increased. Using miniaturized detecting device 1, a plurality of different angular velocities and accelerations are detected at high sensitivity.

In addition, weight portion 18 is formed at end 4 b of second arm 4. Detection sensitivity of the acceleration is improved by an effect of a mass of weight portion 18. At the same time, an amplitude of the driving and oscillation of end 4 b becomes larger to improve detection sensitivity of the angular velocity. In these effects, a product constant (mass×moving speed) becomes larger by weight portion 18 so that a Force de Coriolis caused by driving and oscillation is increased.

Detecting device 1 illustrated in FIG. 1A is formed with weight portion 18. However, weight portion 18 is not always necessary. The effect of the mass of weight portion 18 is exerted by provision of weight portion 18 to improve detection sensitivity of the acceleration and the angular velocity. As illustrated in FIG. 2A, detecting device 1 which does not have weight portion 18 can exert an operation and effect of the present invention. That is to say, in detecting device 1, first arm 2 and second arm 4 are fixed in a substantially orthogonal direction so as to form first orthogonal arm 6. Second arm 4 is folded at folding portions 4 a so that ends 4 b are arranged to face together and first arm 2 is placed between ends 4 b. With this configuration, a plurality of different angular velocities and accelerations are detected by detecting device 1 having simple configuration.

Moreover, second arm 4 is folded at a plurality of folding portions 4 a so that end 4 b may be confronted with second arm 4. Furthermore, as illustrated in FIG. 2B, second arm 4 is folded at a plurality of folding portions 4 a in meander shape so that end 4 b may be confront with second arm 4. Detecting device 1 is thus configured so that the distance between driven and oscillated end 4 b of second arm 4 and base portion 9 to which detecting device 1 is fixed becomes substantially longer. The above operation and effect can be improved. Accordingly, detecting device 1 which has a small mounting area, is miniaturized, and has high detection sensitivity is realized.

A position of the driving and oscillation added to detecting device 1 is not always limited to end 4 b of second arm 4. Other positions of second arm 4 or other arms may be driven and oscillated.

Exemplary Embodiment 2

An inertial force sensor according to exemplary embodiment 2 of the present invention may be of configuration as illustrated in FIG. 3. In the inertial force sensor according to exemplary embodiment 2, the same configuration as that of the inertial force sensor according to exemplary embodiment 1 is indicated by the same reference numerals and the detailed description is omitted.

As illustrated in FIG. 3, in detecting device 1, supporting portion 8 which supports two first arms 2 is fixed to two fixing arms 10. Base portion 9 is formed at end 10 b of each of fixing arms 10. Base portion 9 is fixed to a mounting substrate (not illustrated) on which detecting device 1 is mounted. Ends 4 b of second arm 4 are folded at folding portions 4 a so as to be away from fixing arm 10. Although not illustrated, weight portion 18 may be formed at end 4 b of second arm 4.

In inertial force sensor 20 according to exemplary embodiment 2, as in inertial force sensor 20 according to exemplary embodiment 1, detecting device 1 is integrally molded to a silicon substrate as a material. End 4 b of second arm 4 is the arm which is driven and oscillated. First arm 2, second arm 4, and fixing arm 10 are the arm whose distortion is detected. Accordingly, a driving electrode (not illustrated) is arranged on end 4 b. Detecting electrodes (not illustrated) are arranged on first arm 2, second arm 4, and fixing arm 10.

Moreover, as in exemplary embodiment 1, as illustrated in FIG. 3, driving and oscillation in which a solid arrow line and a dotted arrow line are repeated alternately are added in an X-axis direction of end 4 b, for example. A distortion due to a Force de Coriolis corresponding to the driving and oscillation of end 4 b is detected to detect an angular velocity.

In detecting device 1 illustrated in FIG. 3, the distortion due to acceleration in a Y-axis direction is caused in fixing arm 10. The distortion caused in fixing arm 10 is detected using the detecting electrode to detect acceleration in the Y-axis direction. Accordingly, as in exemplary embodiment 1, detecting device 1 which reduces a mounting area and is miniaturized is realized.

A position of the driving and oscillation added to detecting device 1 is not always limited to end 4 b of second arm 4. Other positions of second arm 4 or other arms may be driven and oscillated.

Exemplary Embodiment 3

FIG. 4A is a plan view of a detecting device used for an inertial force sensor according to exemplary embodiment 3 of the present invention. FIG. 4B is an operation state diagram of the detecting device illustrated in FIG. 4A. In the inertial force sensor according to exemplary embodiment 3, the same configuration as that of the inertial force sensor according to exemplary embodiment 1 or 2 is indicated by the same reference numerals and the detailed description is omitted.

In FIG. 4A, inertial force sensor 20 has detecting device 1 which detects an inertial force and a processing circuit (not illustrated). Detecting device 1 has two first orthogonal arms 6, supporting portion 8, and two fixing arms 10. Each of first orthogonal arms 6 has first arm 2 and second arm 4. First arm 2 is formed so as to be fixed to second arm 4 in a substantially orthogonal direction. Supporting portion 8 supports two first arms 2. Each of fixing arms 10 has one end fixed to supporting portion 8 and end 10 b as the other end formed with base portion 9. Base portion 9 is fixed to a mounting substrate (not illustrated) on which detecting device 1 is mounted. In addition, fixing arm 10 has third arm 12 and fourth arm 14. Third arm 12 is formed so as to be fixed to fourth arm 14 in a substantially orthogonal direction. That is to say, fixing arm 10 configures second orthogonal arm 7 having third arm 12 and fourth arm 14. End 10 b of fixing arm 10 formed with base portion 9 is an end of fourth arm 14 or an end of second orthogonal arm 7. Second arm 4 is folded at folding portions 4 a so that ends 4 b of second arm 4 are confronted with first arm 2. First arm 2 and end 4 b of second arm 4 are arranged to face together and fixing arm 10 is placed between arm 2 and ends 4 b, in appearance. Moreover, second arm 4 is folded at folding portions 4 a so that ends 4 b of second arm 4 are confronted with ends 4 b of another second arm 4.

In detecting device 1, first arm 2 and supporting portion 8 are arranged on a substantially identical straight line. Third arm 12 and supporting portion 8 are arranged on a substantially identical straight line. First arm 2 and third arm 12 are arranged in a substantially orthogonal direction. Relative to an X-axis, a Y-axis, and a Z-axis orthogonal to each other, a longitudinal direction of first arm 2 and a longitudinal direction of fourth arm 14 are arranged in the Y-axis direction, and a longitudinal direction of second arm 4 and a longitudinal direction of third arm 12 are arranged in the X-axis direction.

As in exemplary embodiment 1, detecting device 1 is integrally molded to a silicon substrate as a material. In detecting device 1 illustrated in FIG. 4A, end 4 b of second arm 4 is the arm which is driven and oscillated, and first arm 2, second arm 4, third arm 12, and fourth arm 14 are the arm whose distortion is detected. Accordingly, a driving electrode (not illustrated) is arranged on end 4 b, and detecting electrodes (not illustrated) are arranged on first arm 2, second arm 4, third arm 12, and fourth arm 14. The detecting electrodes need not be always provided on all arms of first arm 2, second arm 4, third arm 12, and fourth arm 14. The detecting electrode should be provided on the arm whose distortion is detected.

With the above configuration, as for an angular velocity, as illustrated in FIG. 4B, when end 4 b of second arm 4 is driven and oscillated in the X-axis direction, a distortion due to an angular velocity about the Z-axis is caused in the Y-axis direction of second arm 4, for example. That is to say, a Force de Coriolis corresponding to the driving and oscillation is caused in the Y-axis direction of second arm 4. At the same time, a distortion due to an angular velocity about the Y-axis is caused in the Z-axis direction of second arm 4. That is to say, a Force de Coriolis corresponding to the driving and oscillation is caused in the Z-axis direction of second arm 4. Accordingly, the distortion caused in the Y-axis direction and the Z-axis direction of second arm 4 is detected to detect an angular velocity produced in detecting device 1. The driving and oscillation in the X-axis direction of end 4 b is driving and oscillation in which a solid arrow line and a dotted arrow line illustrated in FIG. 4B are repeated alternately, for example.

As for acceleration, as illustrated in FIG. 4B, a distortion due to acceleration in the X-axis direction is caused in fourth arm 14, similarly for example. That is to say, forces due to deadweights of first arm 2, second arm 4, and third arm 12 are added to fourth arm 14. At the same time, distortion due to acceleration in the Y-axis direction is caused in third arm 12. That is to say, forces due to deadweights of first arm 2 and second arm 4 are added to third arm 12. Accordingly, the distortion caused in at least one of third arm 12 and fourth arm 14 is detected to detect acceleration produced in detecting device 1.

Thus, a plurality of different inertial forces added to detecting device 1 is detected. Inertial forces of a plurality of different detection axes added to detecting device 1 are detected. Detecting device 1 which reduces a mounting area and is miniaturized is realized.

In detecting device 1 of the present invention, end 4 b of second arm 4 is driven and oscillated, and second arm 4 has a shape folded at folding portion 4 a. Thus, detecting device 1 which has a small mounting area and is miniaturized is realized. In addition, a distance between driven and oscillated end 4 b of second arm 4 and base portion 9 to which detecting device 1 is fixed becomes substantially longer. Detection sensitivity of the angular velocity and the acceleration in each of the directions is increased. Using miniaturized detecting device 1, the angular velocity and the acceleration in each of the directions are detected at high sensitivity. Moreover, detecting device 1 of the present invention has a plurality of different first orthogonal arms 6 and second orthogonal arms 7. Detecting device 1 which has a small mounting area and is excellent in detection sensitivity is realized.

In addition, weight portion 18 is formed at end 4 b of second arm 4. Detection sensitivity of the acceleration is improved by an effect of a mass of weight portion 18. At the same time, an amplitude of the driving and oscillation of end 4 b becomes larger to improve detection sensitivity of the angular velocity. An effect of forming weight portion 18 is similar to that of exemplary embodiment 1.

Detecting device 1 illustrated in FIG. 4A is formed with weight portion 18. Weight portion 18 is not always necessary. As illustrated in FIG. 5A, detecting device 1 which does not have weight portion 18 can exert an operation and effect of the present invention. That is to say, a plurality of different angular velocities and accelerations are detected at high sensitivity.

Moreover, second arm 4 is folded at a plurality of folding portions 4 a so that end 4 b may be confronted with second arm 4. Furthermore, as illustrated in FIG. 5B, second arm 4 is folded at a plurality of folding portions 4 a in meander shape so that end 4 b may be confronted with second arm 4. Detecting device 1 is thus configured to improve the above operation and effect. Accordingly, detecting device 1 which has a small mounting area, is miniaturized, and has high detection sensitivity is realized.

A position of the driving and oscillation added to detecting device 1 is not always limited to end 4 b of second arm 4. Other positions of second arm 4 or other arms may be driven and oscillated.

Exemplary Embodiment 4

FIG. 6A is a plan view of a detecting device used for an inertial force sensor according to exemplary embodiment 4 of the present invention. FIG. 6B is an operation state diagram of the detecting device illustrated in FIG. 6A. In the inertial force sensor according to exemplary embodiment 4, the same configuration as that of the inertial force sensors according to exemplary embodiments 1 to 3 is indicated by the same reference numerals and the detailed description is omitted.

In FIG. 6A, inertial force sensor 20 has detecting device 1 which detects an inertial force and a processing circuit (not illustrated). Detecting device 1 has two first orthogonal arms 6, supporting portion 8, and two fixing arms 10. Each of first orthogonal arms 6 has first arm 2 and second arm 4. First arm 2 is formed so as to be fixed to second arm 4 in a substantially orthogonal direction. Supporting portion 8 supports two first arms 2. Each of fixing arms 10 has one end fixed to supporting portion 8 and end 10 b as the other end formed with base portion 9. Base portion 9 is fixed to a mounting substrate (not illustrated) on which detecting device 1 is mounted. In addition, second arm 4 is folded at folding portions 4 a so that ends 4 b of second arm 4 are confronted with second arm 4. Weight portion 18 is formed at end 4 b of second arm 4.

In detecting device 1, first arm 2 and supporting portion 8 are arranged on a substantially identical straight line. Fixing arm 10 and supporting portion 8 are arranged on a substantially identical straight line. First arm 2 and fixing arm 10 are arranged in a substantially orthogonal direction. Relative to an X-axis, a Y-axis, and a Z-axis orthogonal to each other, a longitudinal direction of first arm 2 is arranged in the Y-axis direction and a longitudinal direction of second arm 4 is arranged in the X-axis direction.

As in exemplary embodiment 1, detecting device 1 is integrally molded to a silicon substrate as a material. In detecting device 1 illustrated in FIG. 6A, end 4 b of second arm 4 is the arm which is driven and oscillated, and first arm 2, second arm 4, and fixing arm 10 are the arm whose distortion is detected. A driving electrode (not illustrated) is arranged at end 4 b. Detecting electrodes (not illustrated) are arranged on first arm 2, second arm 4, and fixing arm 10. The detecting electrodes need not be always provided on all arms of first arm 2, second arm 4, and fixing arm 10. The detecting electrode should be provided on the arm whose distortion is detected.

With the above configuration, as for an angular velocity, as illustrated in FIG. 6B, when end 4 b of second arm 4 is driven and oscillated in the Y-axis direction, a distortion due to an angular velocity about the Z-axis is caused in the X-axis direction of first arm 2, for example. That is to say, a Force de Coriolis corresponding to the driving and oscillation is caused in the X-axis direction of second arm 4. At the same time, a distortion due to an angular velocity about the X-axis is caused in the Z-axis direction of second arm 4. That is to say, a Force de Coriolis corresponding to the driving and oscillation is caused in the Z-axis direction of second arm 4. Accordingly, the distortion caused in the X-axis direction of first arm 2 and the Z-axis direction of second arm 4 is detected to detect an angular velocity produced in detecting device 1. The driving and oscillation in the Y-axis direction of end 4 b are driving and oscillation in which a solid arrow line and a dotted arrow line illustrated in FIG. 6B are repeated alternately, for example.

As for acceleration, as illustrated in FIG. 6B, a distortion due to acceleration in the X-axis direction is caused in first arm 2, for example. That is to say, a force due to a deadweight of second arm 4 is added to first arm 2. At the same time, a distortion due to acceleration in the Y-axis direction is caused in fixing arm 10. That is to say, forces due to deadweights of first arm 2 and second arm 4 are added to fixing arm 10. Accordingly, the distortion caused in at least one of first arm 2 and fixing arm 10 is detected to detect acceleration produced in detecting device 1.

Thus, a plurality of different inertial forces added to detecting device 1 is detected. Inertial forces of a plurality of different detection axes added to detecting device 1 are detected. Detecting device 1 which reduces a mounting area and is miniaturized is realized.

In detecting device 1, second arms 4 are folded at folding portions 4 a so that second arms 4 are arranged so as to be confronted with each other. Thus, detecting device 1 which has a small mounting area and is miniaturized is realized. In addition, end 4 b of second arm 4 is driven and oscillated to detect the distortion of each of the arms. That is to say, detecting device 1 is thus configured so that a distance between driven and oscillated end 4 b of second arm 4 and base portion 9 to which detecting device 1 is fixed becomes substantially longer. An amplitude of the driving and oscillation of end 4 b becomes larger to improve detection sensitivity of the angular velocity. Using miniaturized detecting device 1, a plurality of different angular velocities and accelerations are detected at high sensitivity.

In addition, weight portion 18 b is formed at end 4 b of second arm 4. Detection sensitivity of the acceleration is improved by an effect of a mass of weight portion 18. At the same time, an amplitude of the driving and oscillation of end 4 b becomes larger to improve detection sensitivity of the angular velocity. An effect of forming weight portion 18 is similar to that of exemplary embodiment 1.

Detecting device 1 illustrated in FIG. 6A is formed with weight portion 18. Weight portion 18 is not always necessary. As illustrated in FIG. 7A, detecting device 1 which does not have weight portion 18 can exert an operation and effect of the present invention. That is to say, a plurality of different angular velocities and accelerations are detected at high sensitivity.

Moreover, second arm 4 is folded at a plurality of folding portions 4 a so that end 4 b may be confronted with second arm 4. Furthermore, as illustrated in FIG. 7B, second arm 4 is folded at a plurality of folding portions 4 a in meander shape so that end 4 b may be confronted with second arm 4. Detecting device 1 is thus configured to improve detection sensitivity of the angular velocity. Detecting device 1 which has a small mounting area, is miniaturized, and has high detection sensitivity is realized.

A position of the driving and oscillation added to detecting device 1 is not always limited to end 4 b of second arm 4. Other positions of second arm 4 or other arms may be driven and oscillated.

Exemplary Embodiment 5

FIG. 8A is a plan view of a detecting device used for an inertial force sensor according to exemplary embodiment 5 of the present invention. FIG. 8B is an operation state diagram of the detecting device illustrated in FIG. 8A. In the inertial force sensor according to exemplary embodiment 5, the same configuration as that of the inertial force sensors according to exemplary embodiments 1 to 4 is indicated by the same reference numerals and the detailed description is omitted.

In FIG. 8A, inertial force sensor 20 has detecting device 1 which detects an inertial force and a processing circuit (not illustrated). Detecting device 1 has two first orthogonal arms 6, supporting portion 8, and two fixing arms 10. Each of first orthogonal arms 6 has first arm 2 and second arm 4. First arm 2 is formed so as to be fixed to second arm 4 in a substantially orthogonal direction. Supporting portion 8 supports two first arms 2. Each of fixing arms 10 has one end fixed to supporting portion 8 and end 10 b as the other end formed with base portion 9. Base portion 9 is fixed to a mounting substrate (not illustrated) on which detecting device 1 is mounted. In addition, fixing arm 10 has third arm 12 and fourth arm 14. Third arm 12 is formed so as to be fixed to fourth arm 14 in a substantially orthogonal direction. That is to say, fixing arm 10 configures second orthogonal arm 7 having third arm 12 and fourth arm 14. End 10 b of fixing arm 10 formed with base portion 9 is an end of fourth arm 14 and also an end of second orthogonal arm 7. At least a part of third arm 12 serves as first arm 2. Second arm 4 is folded at folding portions 4 a so that ends 4 b of second arm 4 are confronted with second arm 4 mutually. Second arm 4 is folded at folding portions 4 a so that ends 4 b of second arm 4 are confronted with fourth arm 14.

In detecting device 1, third arm 12 and supporting portion 8 are arranged on a substantially identical straight line. In other words, first arm 2 and supporting portion 8 are arranged on a substantially identical straight line. Relative to an X-axis, a Y-axis, and a Z-axis orthogonal to each other, a longitudinal direction of first arm 2 and a longitudinal direction of third arm 12 are arranged in the Y-axis direction, and a longitudinal direction of second arm 4 and a longitudinal direction of fourth arm 14 are arranged in the X-axis direction.

As in exemplary embodiment 1, detecting device 1 is integrally molded to a silicon substrate as a material. In detecting device 1 illustrated in FIG. 8A, end 4 b of second arm 4 is the arm which is driven and oscillated, and first arm 2, second arm 4, and fixing arm 10 are the arm whose distortion is detected. A driving electrode (not illustrated) is arranged on end 4 b. Detecting electrodes (not illustrated) are arranged on first arm 2, second arm 4, third arm 12, and fourth arm 14. The detecting electrodes need not be always provided on all arms of first arm 2, second arm 4, third arm 12, and fourth arm 14. The detecting electrode should be provided on the arm whose distortion is detected.

With the above configuration, as for an angular velocity, as illustrated in FIG. 8B, when end 4 b of second arm 4 is driven and oscillated in the Y-axis direction, a distortion due to an angular velocity about the Z-axis is caused in the X-axis direction of third arm 12, for example. That is to say, a Force de Coriolis corresponding to the driving and oscillation is caused in the X-axis direction of second arm 4. At the same time, a distortion due to an angular velocity about the X-axis is caused in the Z-axis direction of second arm 4, third arm 12, and fourth arm 14. That is to say, a Force de Coriolis corresponding to the driving and oscillation is caused in the Z-axis direction of second arm 4, third arm 12, and fourth arm 14. Accordingly, the distortion caused in the Y-axis direction of second arm 4 and the Z-axis direction of at least one of second arm 4, third arm 12, and fourth arm 14 is detected to detect an angular velocity produced in detecting device 1. The driving and oscillation in the Y-axis direction of end 4 b are driving and oscillation in which a solid arrow line and a dotted arrow line illustrated in FIG. 8B are repeated alternately, for example.

As for acceleration, as illustrated in FIG. 8B, a distortion due to acceleration in the X-axis direction is caused in third arm 12, for example. That is to say, a force due to a deadweight of second arm 4 is added to third arm 12. At the same time, a distortion due to acceleration in the Y-axis direction is caused in fourth arm 14. That is to say, forces due to deadweights of second arm 4 and third arm 12 are added to fourth arm 14. Accordingly, the distortion caused in at least one of third arm 12 and fourth arm 14 is detected to detect acceleration produced in detecting device 1.

Thus, a plurality of different inertial forces added to detecting device 1 is detected. Inertial forces of a plurality of different detection axes added to detecting device 1 are detected. Detecting device 1 which reduces a mounting area and is miniaturized is realized.

In detecting device 1, second arms 4 are folded at folding portions 4 a so that second arms 4 are arranged so as to be confronted with each other. Thus, detecting device 1 which has a small mounting area and is miniaturized is realized. In addition, end 4 b of second arm 4 is driven and oscillated to detect the distortion of each of the arms. That is to say, detecting device 1 is thus configured so that a distance between driven and oscillated end 4 b of second arm 4 and base portion 9 to which detecting device 1 is fixed becomes substantially longer. An amplitude of the driving and oscillation of end 4 b becomes larger to improve detection sensitivity of an angular velocity. Using miniaturized detecting device 1, a plurality of different angular velocities and accelerations are detected at high sensitivity.

Moreover, second arm 4 is folded at a plurality of folding portions 4 a so that end 4 b may be confronted with second arm 4. Furthermore, as illustrated in FIG. 9, second arm 4 is folded at a plurality of folding portions 4 a in meander shape so that end 4 b may be confronted with second arm 4. Detecting device 1 is thus configured to improve detection sensitivity of the angular velocity. Detecting device 1 which has a small mounting area, is miniaturized, and has high detection sensitivity is realized.

In addition, weight portion 18 is formed at end 4 b of second arm 4. Detection sensitivity of acceleration is improved. An amplitude of the driving and oscillation of end 4 b becomes larger to improve detection sensitivity of the angular velocity.

Accordingly, as illustrated in FIG. 10, when second arm 4 is folded at folding portions 4 a so that ends 4 b are confronted with second arm 4 and weight portion 18 is formed at end 4 b, detection sensitivity of both the angular velocity and acceleration is improved.

A position of the driving and oscillation added to detecting device 1 is not always limited to end 4 b of second arm 4. Other positions of second arm 4 or other arms may be driven and oscillated.

Exemplary Embodiment 6

FIG. 11 is a plan view of a detecting device used for an inertial force sensor according to exemplary embodiment 6 of the present invention. FIG. 12 is an operation state diagram of the detecting device illustrated in FIG. 11. In the inertial force sensor according to exemplary embodiment 6, the same configuration as that of the inertial force sensors according to exemplary embodiments 1 to 5 is indicated by the same reference numerals and the detailed description is omitted.

In FIG. 11, inertial force sensor 20 has detecting device 1 which detects an inertial force and a processing circuit (not illustrated). Detecting device 1 has two first orthogonal arms 6, supporting portion 8, and two fixing arms 10. Each of first orthogonal arms 6 has first arm 2 and second arm 4. First arm 2 is formed so as to be fixed to second arm 4 in a substantially orthogonal direction. Supporting portion 8 supports two first arms 2. Each of fixing arms 10 has one end fixed to supporting portion 8 and end 10 b as the other end formed with base portion 9. Base portion 9 is fixed to a mounting substrate (not illustrated) on which detecting device 1 is mounted. At least a part of fixing arm 10 serves as first arm 2.

In detecting device 1, fixing arm 10 and supporting portion 8 are arranged on a substantially identical straight line. In other words, first arm 2 and supporting portion 8 are arranged on a substantially identical straight line. Relative to an X-axis, a Y-axis, and a Z-axis orthogonal to each other, a longitudinal direction of first arm 2 and a longitudinal direction of fixing arm 10 are arranged in the Y-axis direction, and a longitudinal direction of second arm 4 is arranged in the X-axis direction.

As in exemplary embodiment 1, detecting device 1 is integrally molded to a silicon substrate as a material. In detecting device 1 illustrated in FIG. 11, end 4 b of second arm 4 is the arm which is driven and oscillated, and second arm 4 and fixing arm 10 are the arm whose distortion is detected. A driving electrode (not illustrated) is arranged on end 4 b. Detecting electrodes (not illustrated) are arranged on second arm 4 and fixing arm 10. The detecting electrodes need not be always provided on all arms of first arm 2, second arm 4, and fixing arm 10. The detecting electrode should be provided on the arm whose distortion is detected.

With the above configuration, as for an angular velocity, as illustrated in FIG. 12, when end 4 b of second arm 4 is driven and oscillated in the Y-axis direction, a distortion due to an angular velocity about the Z-axis is caused in the X-axis direction of fixing arm 10, for example. That is to say, a Force de Coriolis corresponding to the driving and oscillation is caused in the X-axis direction of second arm 4. At the same time, a distortion caused in an angular velocity about the X-axis is caused in the Z-axis direction of fixing arm 10 and second arm 4. That is to say, a Force de Coriolis corresponding to the driving and oscillation is caused in the Z-axis direction of second arm 4 and fixing arm 10. Accordingly, the distortion caused in the X-axis direction of fixing arm 10 and the Z-axis direction of at least one of second arm 4 and fixing arm 10 is detected to detect an angular velocity produced in detecting device 1. The driving and oscillation in the Y-axis direction of end 4 b are driving and oscillation in which a solid arrow line and a dotted arrow line illustrated in FIG. 12 are repeated alternately, for example.

As for acceleration, as illustrated in FIG. 12, a distortion due to acceleration in the X-axis direction is caused in fixing arm 10, for example. That is to say, a force due to a deadweight of second arm 4 is added to fixing arm 10. At the same time, a distortion due to acceleration in the Y-axis direction is caused in second arm 4. A force due to a deadweight of second arm 4 is added to second arm 4. Accordingly, the distortion caused in at least one of fixing arm 10 and second arm 4 is detected to detect acceleration produced in detecting device 1.

Thus, a plurality of different inertial forces added to detecting device 1 is detected. Inertial forces of a plurality of different detection axes added to detecting device 1 are detected. Detecting device 1 which reduces a mounting area and is miniaturized is realized.

In addition, as illustrated in FIG. 13, weight portion 18 is formed at end 4 b of second arm 4. Detection sensitivity of acceleration is improved. An amplitude of the driving and oscillation of end 4 b becomes larger to improve detection sensitivity of the angular velocity.

Moreover, as illustrated in FIG. 14A, second arm 4 is folded at a plurality of folding portions 4 a so that end 4 b may be confronted with second arm 4. Furthermore, as illustrated in FIG. 14B, second arm 4 is folded at a plurality of folding portions 4 a in meander shape so that end 4 b may be confronted with second arm 4. Detecting device 1 is thus configured so that an amplitude of the driving and oscillation of end 4 b becomes larger to improve detection sensitivity of the angular velocity. Detecting device 1 which has a small mounting area, is miniaturized, and has high detection sensitivity is realized.

A position of the driving and oscillation added to detecting device 1 is not always limited to end 4 b of second arm 4. Other positions of second arm 4 or other arms may be driven and oscillated.

INDUSTRIAL APPLICABILITY

The inertial force sensor according to the present invention can detect a plurality of inertial forces and inertial forces of a plurality of detection axes and is applicable to various electronic devices. 

1. An inertial force sensor comprising: a detecting device which detects an inertial force, wherein the detecting device includes: two first orthogonal arms, each of which has a first arm and a second arm and is formed by fixing the first arm and the second arm in a substantially orthogonal direction; and a supporting portion which supports the first arm, wherein the second arm has a folding portion which folds the second arm, and wherein the second arm is folded at the folding portion and confronted with the first arm.
 2. The inertial force sensor according to claim 1, wherein the first arm and the supporting portion are arranged on a substantially identical straight line.
 3. The inertial force sensor according to claim 1, wherein an end of the second arm is driven and oscillated in a direction confronting the first arm, and wherein an angular velocity is detected by detecting distortion of the first arm or the second arm.
 4. The inertial force sensor according to claim 1, wherein acceleration is detected by detecting distortion of the first arm or the second arm.
 5. The inertial force sensor according to claim 1, wherein the detecting device further includes a weight portion formed at an end of the second arm.
 6. The inertial force sensor according to claim 1, wherein an end of the second arm is folded in meander shape.
 7. An inertial force sensor comprising: a detecting device which detects an inertial force, wherein the detecting device includes: two first orthogonal arms, each of which has a first arm and a second arm and is formed by fixing the first arm and the second arm in a substantially orthogonal direction; and a supporting portion which supports the first arm, wherein the second arm has a folding portion which folds the second arm, wherein the detecting device further includes two fixing arms which are fixed to the supporting portion and fixed to a mounting substrate on which the detecting device is to be mounted, wherein the fixing arm is a second orthogonal arm, which has a third arm and a fourth arm and is formed by fixing the third arm and the fourth arm in a substantially orthogonal direction, wherein the third arm is supported by the supporting portion, wherein the fixing arm is fixed to the mounting substrate by the fourth arm, wherein the first arm and the supporting portion are arranged on a substantially identical straight line, wherein the third arm and the supporting portion are arranged on a substantially identical straight line, and wherein the first arm and the third arm are arranged in a substantially orthogonal direction.
 8. An inertial force sensor comprising: a detecting device which detects an inertial force, wherein the detecting device includes: two first orthogonal arms, each of which has a first arm and a second arm and is formed by fixing the first arm and the second arm in a substantially orthogonal direction; and a supporting portion which supports the first arm, wherein the second arm has a folding portion which folds the second arm, wherein the detecting device further includes two fixing arms which are fixed to the supporting portion and fixed to a mounting substrate on which the detecting device is to be mounted, wherein the second arm is folded at the folding portion and confronted with the second arm, wherein the first arm and the supporting portion are arranged on a substantially identical straight line, wherein the fixing arm and the supporting portion are arranged on a substantially identical straight line, and wherein the first arm and the fixing arm are arranged in a substantially orthogonal direction. 